Adobe software currently prefers using a video card set of software called 'CUDA', this contrasts with Apple's Final Cut Pro X software which prefers using 'OpenCL'. CUDA is a proprietary standard to Nvidia so this means for Adobe software you currently get better results with an Nvidia graphics card for your Mac.
Note: As OpenCL is an open standard (the clue is in the name 🙂) it does also work on Nvidia cards as well as AMD cards but historically AMD cards have been better optimised for OpenCL.
This situation may change in the future. Apple have written a new standard called 'Metal'. Again Metal works on both Nvidia and AMD cards but the possible change here is that Adobe have tested using Metal and been very impressed with it and hence might in the future be switching away from using CUDA to using Metal. As a result the current need to use Nvidia cards to get the best results with Adobe software may no longer be necessary.
So getting to specifics, as Nvidia will currently be the best option for you, you need to look ideally for an Nvidia card. This could be a GTX-680, or GTX-780, or GTX-980.
Note: The GTX-680 was available as an official Mac compatible card but the 780 and 980 are not. You can use the PC versions of these cards in a Mac and they will work but you do not get the boot screen. There is a reseller who does offer 'flashed' 780 and 980 cards which have Mac firmware added so that they do support standard Mac boot screen options. See http://www.macvidcards.com/store/c2/Nvidia_GPUs.html